Cократить дробь:

х^2-у^2
__________

3х-2х^2+3y-2xy

(x-y)(x+y) / (3x+3y)-(2x^2+2xy)=
(x-y)(x+y) / 3(x+y)-2x(x+y)=
(x-y)(x+y) / (x+y)(3-2x)=
x-y / 3-2x